A100 PCIe 40GB

The A100 PCIe 40GB is a Ampere-generation NVIDIA GPU built on the GA100 architecture, manufactured on a TSMC 7nm process node with 54.2 billion transistors. Released in 2020, it delivers 312 TFLOPS of FP16 throughput and 312 TFLOPS BF16 — the two precision formats most commonly used for transformer model training and inference. The GA100 architecture represents NVIDIA's approach to balancing compute throughput, memory bandwidth, and power efficiency for data center AI workloads. At 250W TDP, the A100 PCIe 40GB sits in the moderate power envelope (250W), suitable for both workstation and data center deployments.

Memory capacity is 40GB of HBM2e with 1555 GB/s bandwidth. This determines which models can run without quantization: approximately 20B parameters at FP16 (2 bytes/param), 40B at INT8 (1 byte/param), or up to 80B parameters at INT4/GGUF quantization (0.5 bytes/param). These figures are theoretical maximums — actual capacity is reduced by KV cache, framework overhead, and activation memory, typically by 10–20% for inference and 30–40% for training. The arithmetic intensity ceiling is approximately 201 FLOP/byte (312 TFLOPS ÷ 1555 GB/s). Most autoregressive LLM inference falls well below this threshold, making the 1555 GB/s memory bandwidth the binding constraint on tokens-per-second throughput rather than raw TFLOPS.

The A100 PCIe 40GB uses PCIe 4.0 for host connectivity. Without NVLink, VRAM cannot be pooled across multiple cards — the single-card 40GB capacity is the hard ceiling for model size without model sharding over slower PCIe. For workloads that exceed 40GB, the alternative is pipeline parallelism (splitting model layers across cards) rather than tensor parallelism, which introduces inter-card communication overhead at each layer boundary. This makes the A100 PCIe 40GB best suited for workloads that fit within a single card's VRAM budget.

The primary workloads for the A100 PCIe 40GB are Mid-size model inference, Cost-efficient training, Research workloads. PCIe form factor A100 40GB. Same compute as 80GB variant but half the VRAM. Lowest cost A100 option. Suitable for models up to ~30B parameters. Key limitations to factor into your evaluation: No NVLink — cannot pool VRAM across cards; Lower memory bandwidth than SXM4 variant; No FP8 support — lower throughput than H100 for transformer workloads. When comparing this GPU against alternatives at similar price points, the most important metrics are memory bandwidth (for inference throughput), VRAM capacity (for model size), and FP16/BF16 TFLOPS (for training speed). Raw TFLOPS figures can be misleading for inference — a GPU with lower TFLOPS but higher memory bandwidth will often outperform a higher-TFLOPS card on tokens-per-second for memory-bound autoregressive generation.

In the broader GPU market, the A100 PCIe 40GB is a 6-year-old design that is increasingly being replaced by newer architectures in cloud deployments, though it remains available at competitive rental rates. CUDA compatibility is a significant advantage: the A100 PCIe 40GB benefits from the full NVIDIA software ecosystem including cuDNN, TensorRT, FlashAttention, and all major inference frameworks (vLLM, TGI, TensorRT-LLM). CUDA's maturity means optimized kernels are available for virtually every model architecture. For cloud rental, availability varies significantly by provider — some specialize in this GPU tier while others may have limited stock. Compare on-demand and spot pricing across providers using the rental comparison table on this page, and factor in region availability if latency is a concern for your inference workload.